This invention relates to cylinder head assemblies for internal combustion engines. More particularly, this invention relates to engine cylinder head assemblies having a cast component and a non-cast component.
A typical prior art engine cylinder head assembly includes two die cast components or elements. Such cylinder head assemblies are expensive to manufacture since two castings, and the tooling for two different castings, are required.
To overcome the high cost of cylinder heads having two cast components, it has been proposed to manufacture an integral cylinder head comprised of a single casting. However, the casting, and the tooling for such a casting, are very complex and expensive to manufacture.
Typical prior art overhead valve (OHV) cylinder heads have two valve train-rocker assemblies for opening and closing the intake and the exhaust valves. In typical prior art cylinder heads, a boss must be formed in a casting to receive the stud bolt used to hold each of the two rocker arms in place. After the boss is formed, it must be drilled or otherwise machined, and the rocker stud must be threaded into the machined hole. These extra steps further increase the cost of the cylinder head assembly.
Also, in typical prior art cylinder head assemblies, it is necessary to provide guides for the push rods which operate the intake and exhaust valves. The push rod guides are typically incorporated into a separate plate that is affixed to the head by rocker studs, or by other means. The use of a separate plate increases the cost of the head assembly.